An axial flow steam turbine typically includes sealing strips and also sealing segments forming part of shaft sealing assemblies. Their function is to provide contact free sealing between the turbine rotor and turbine inner casing in order to avoid a leakage flow. Due to high mechanical and thermal stress, oxidation, corrosion or blade rubbing, sealing strips can be damaged. The result is a higher leakage of the flow area and a decrease of turbine efficiency. In order to prevent the efficiency deficit, the damaged sealing strips have to be replaced.
DE215065C discloses a milling device to cutting slots in wood. The device includes holding plates that contains a cutter mounted at one end. The holding plates themselves are slidably in a body to enable lowering and raising of the cutter and further containing a drive shaft at a distal end of the holder holding plates.
A method of removing such sealing strips is discussed in U.S. Pat. No. 8,276,488. The method involves removing the turbine to a workshop, separating the casing into half-casings, and removing both the stator and rotor blades to access the seal fins and caulking wire. The old fins are then machined down to access the caulking wire which is carefully machined out to avoid damaging the grooves of the half-casings. Replacement fins and caulking wire are then mounted in the grooves, and the replacement fins are machined down to precise clearances from the rotor shaft and blades. A requirement of the tool is that blades rows needs to be removed in order to access the sealing fins. This adds both complexity and time to the task.